internal var direction = SDirection.column

internal var justifyContent = SJustifyContent.start

internal var alignItems = SAlignItems.stretch

internal var _paddingTop: Value?

internal var _paddingLeft: Value?

internal var _paddingStart: Value?

internal var _paddingBottom: Value?

internal var _paddingRight: Value?

internal var _paddingEnd: Value?

public override init(frame: CGRect) {

super.init(frame: frame)

translatesAutoresizingMaskIntoConstraints = false

}

public required init?(coder aDecoder: NSCoder) {

super.init(coder: aDecoder)

translatesAutoresizingMaskIntoConstraints = false

}

public static override var requiresConstraintBasedLayout: Bool {

return false

}

/**

This method is used to structure your code so that it matches the stack view structure. The method has a closure parameter with a

single parameter called `stackView`. This parameter is in fact the StackView instance, it can be used to adds items

to the StackView.

- Parameter closure:

*/

@discardableResult

public func define(_ closure: (_ stackView: StackView) -> Void) -> StackView {

closure(self)

return self

}

@discardableResult

public func addStackView() -> StackView {

let stackView = StackView()

addItem(stackView)

return stackView

}

@discardableResult

public func addItem(_ view: UIView) -> StackItem {

view.translatesAutoresizingMaskIntoConstraints = false

addSubview(view)

markDirty()

return view.item

}

@discardableResult

public func insertItem(_ view: UIView, at index: Int) -> StackItem {

view.translatesAutoresizingMaskIntoConstraints = false

insertSubview(view, at: index)

markDirty()

return view.item

}

@discardableResult

public func insertItem(_ view: UIView, before refItem: UIView) -> StackItem? {

view.translatesAutoresizingMaskIntoConstraints = false

insertSubview(view, aboveSubview: refItem)

markDirty()

return view.item

}

@discardableResult

public func insertItem(_ view: UIView, after refItem: UIView) -> StackItem? {

view.translatesAutoresizingMaskIntoConstraints = false

insertSubview(view, belowSubview: refItem)

markDirty()

return view.item

}

public func removeItem(_ view: UIView) {

view.removeFromSuperview()

markDirty()

}

/**

The `direction` property establishes the main-axis, thus defining the direction items are placed in the StackView.

The `direction` property specifies how items are laid out in the StackView, by setting the direction of the StackView’s main axis. They can be laid out in two main directions, like columns vertically or like rows horizontally.

- Parameter value: Default value is .column

*/

@discardableResult

public func direction(_ value: SDirection) -> StackView {

direction = value

markDirty()

return self

}

public func getDirection() -> SDirection {

return direction

}

/**

The `justifyContent` property defines the alignment along the main-axis of the StackView.

It helps distribute extra free space leftover when either all the items on a line have reached their maximum

size. For example, if items are flowing vertically, `justifyContent` controls how they align vertically.

- Parameter value: Default value is .start

*/

@discardableResult

public func justifyContent(_ value: SJustifyContent) -> StackView {

justifyContent = value

markDirty()

return self

}

public func getJustifyContent() -> SJustifyContent {

return justifyContent

}

/**

The `alignItems` property defines how items are laid out along the cross-axis in the StackView.

Similar to `justifyContent` but for the cross-axis (perpendicular to the main-axis). For example, if

items are flowing vertically, `alignItems` controls how they align horizontally.

- Parameter value: Default value is .stretch

*/

@discardableResult

public func alignItems(_ value: SAlignItems) -> StackView {

alignItems = value

markDirty()

return self

}

public func getAlignItems() -> SAlignItems {

return alignItems

}

//

// MARK: Padding

//

/**

Set the top padding. Top padding specify the **offset children should have** from the container's top edge.

*/

@discardableResult

public func paddingTop(_ value: CGFloat) -> StackView {

_paddingTop = Value(value)

return self

}

/**

Set the left padding. Left padding specify the **offset children should have** from the container's left edge.

*/

@discardableResult

public func paddingLeft(_ value: CGFloat) -> StackView {

_paddingLeft = Value(value)

return self

}

/**

Set the bottom padding. Bottom padding specify the **offset children should have** from the container's bottom edge.

*/

@discardableResult

public func paddingBottom(_ value: CGFloat) -> StackView {

_paddingBottom = Value(value)

return self

}

/**

Set the top padding. Top padding specify the **offset children should have** from the container's top edge.

*/

@discardableResult

public func paddingRight(_ value: CGFloat) -> StackView {

_paddingRight = Value(value)

return self

}

/**

Set the start padding.

Depends on the item `LayoutDirection`:

* In LTR direction, start padding specify the **offset children should have** from the container's left edge.

* IN RTL direction, start padding specify the **offset children should have** from the container's right edge.

*/

@discardableResult

public func paddingStart(_ value: CGFloat) -> StackView {

_paddingStart = Value(value)

return self

}

/**

Set the end padding.

Depends on the item `LayoutDirection`:

* In LTR direction, end padding specify the **offset children should have** from the container's right edge.

* IN RTL direction, end padding specify the **offset children should have** from the container's left edge.

*/

@discardableResult

public func paddingEnd(_ value: CGFloat) -> StackView {

_paddingEnd = Value(value)

return self

}

/**

Set the left, right, start and end paddings to the specified value.

*/

@discardableResult

public func paddingHorizontal(_ value: CGFloat) -> StackView {

_paddingLeft = Value(value)

_paddingRight = Value(value)

return self

}

/**

Set the top and bottom paddings to the specified value.

*/

@discardableResult

public func paddingVertical(_ value: CGFloat) -> StackView {

_paddingTop = Value(value)

_paddingBottom = Value(value)

return self

}

/**

Set paddings using UIEdgeInsets.

This method is particularly useful to set all paddings using iOS 11 `UIView.safeAreaInsets`.

*/

@discardableResult

public func padding(insets: UIEdgeInsets) -> StackView {

_paddingTop = Value(insets.top)

_paddingLeft = Value(insets.left)

_paddingBottom = Value(insets.bottom)

_paddingRight = Value(insets.right)

return self

}

/**

Set paddings using NSDirectionalEdgeInsets.

This method is particularly to set all paddings using iOS 11 `UIView.directionalLayoutMargins`.

Available only on iOS 11 and higher.

*/

@available(tvOS 11.0, iOS 11.0, *)

@discardableResult

func padding(dirInsets: NSDirectionalEdgeInsets) -> StackView {

_paddingTop = Value(dirInsets.top)

_paddingStart = Value(dirInsets.leading)

_paddingBottom = Value(dirInsets.bottom)

_paddingEnd = Value(dirInsets.trailing)

return self

}

/**

Set all paddings to the specified value.

*/

@discardableResult

public func padding(_ value: CGFloat) -> StackView {

_paddingTop = Value(value)

_paddingBottom = _paddingTop

_paddingLeft = _paddingTop

_paddingRight = _paddingTop

return self

}

/**

Set the individually vertical paddings (top, bottom) and horizontal paddings (left, right, start, end).

*/

@discardableResult func padding(_ vertical: CGFloat, _ horizontal: CGFloat) -> StackView {

paddingVertical(vertical)

paddingHorizontal(horizontal)

return self

}

/**

Set the individually top, horizontal paddings and bottom padding.

*/

@discardableResult func padding(_ top: CGFloat, _ horizontal: CGFloat, _ bottom: CGFloat) -> StackView {

_paddingTop = Value(top)

paddingHorizontal(horizontal)

_paddingBottom = Value(bottom)

return self

}

/**

Set the individually top, left, bottom and right paddings.

*/

@discardableResult

public func padding(_ top: CGFloat, _ left: CGFloat, _ bottom: CGFloat, _ right: CGFloat) -> StackView {

_paddingTop = Value(top)

_paddingLeft = Value(left)

_paddingBottom = Value(bottom)

_paddingRight = Value(right)

return self

}

//

// Layout view

//

/**

StackView's items are layouted only when a item's property is changed and when the StackView size change.

In the event that you want to force StackView to do a layout of its items, you can mark it as dirty

using `markDirty()`.

*/

public func markDirty() {

setNeedsLayout()

// All StackViews ancestors dirty.

if let stackView = superview as? StackView {

stackView.markDirty()

}

}

//

// MARK: UIView Visual properties

//

/**

Set the item/view background color.

*/

@discardableResult

public func backgroundColor(_ color: UIColor) -> StackView {

backgroundColor = color

return self

}

/**

Set the item/view transparency `alpha`.

*/

@discardableResult

public func alpha(_ value: CGFloat) -> StackView {

alpha = value

return self

}

//

// Show/hide items

//

public func hideItem(_ view: UIView, animate: Bool) {

guard let stackItemImpl = view.item as? StackItemImpl else { return }

stackItemImpl.isHidden = true

// updateItemVisibility(view: view, isVisible: false, animate: animate)

}

public func showItem(_ view: UIView, animate: Bool) {

// updateItemVisibility(view: view, isVisible: true, animate: animate)

}

// internal func updateItemVisibility(view: UIView, isVisible: Bool, animate: Bool) {

// guard let stackItemImpl = view.item as? StackItemImpl else { return }

// guard let itemIndex = stackItems.index(of: stackItemImpl) else { print("The view is not part of this stackView!"); return }

// let duration = 0.3

//

// if animate {

// if isVisible {

// view.bounds.size = direction == .column ? CGSize(width: view.frame.width, height: 0) : CGSize(width: 0, height: view.frame.height)

// view.isHidden = false

//

// UIView.animate(withDuration: duration, delay: 0, options: [.beginFromCurrentState], animations: {

// self.forceLayoutNow()

// })

// } else {

// let itemSnapshot = view.snapshotView(afterScreenUpdates: true)!

// itemSnapshot.frame = view.frame

// insertSubview(itemSnapshot, at: itemIndex)

// view.isHidden = true

//

// UIView.animate(withDuration: duration, delay: 0, options: [.beginFromCurrentState], animations: {

// itemSnapshot.frame.size = self.direction == .column ? CGSize(width: itemSnapshot.frame.width, height: 0) : CGSize(width: 0, height: itemSnapshot.frame.height)

// self.forceLayoutNow()

// }, completion: { (completed) in

// itemSnapshot.removeFromSuperview()

// })

// }

// } else {

// view.isHidden = !isVisible

// forceLayoutNow()

// }

// }

// internal func forceLayoutNow() {

// setNeedsLayout()

// layoutIfNeeded()

// }

// TODO_: Tests StackView using autolayout

public override var intrinsicContentSize: CGSize {

return sizeThatFits(CGSize(width: frame.width, height: .greatestFiniteMagnitude))

}

// TODO_: Tests StackView using autolayout

public override func systemLayoutSizeFitting(_ targetSize: CGSize) -> CGSize {

return sizeThatFits(targetSize)

}

public override func layoutSubviews() {

super.layoutSubviews()

let container = Container(stackView: self)

layoutItems(container: container, mode: .layouting)

}

public override func sizeThatFits(_ size: CGSize) -> CGSize {

let container = Container(stackView: self, size: size)

return layoutItems(container: container, mode: .measuring)

}